Carbon fiber insert for ballet shoe

ABSTRACT

An insert for a ballet pointe shoe includes an aft section positionable adjacent the heel of the shoe or between the heel and the box of the shoe, and a forward section positionable adjacent the platform and under the box. A distal end of the forward section is shaped in complement to the platform. The insert is formed of carbon fiber. The construction resists breaking down with use and can significantly reduce the cost of pointe shoes for ballet dancers while also decreasing the risk of injury.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 62/638,393, filed Mar. 5, 2018, the entire content of which is herein incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

(NOT APPLICABLE)

BACKGROUND

The invention relates to an insert for a ballet pointe shoe constructed of carbon fiber.

The traditional design and materials for a ballet pointe shoe have been used for almost 200 years with very few advances. A pointe shoe consists of many parts made from various materials in order to keep a dancer on her toes. The square stiff piece that encapsulates the toes is known as the box of the shoe. The box is typically made from layers of fabric, cardboard, burlap, and paper and held together by an adhesive known as Nitrocellulose. All of the dancer's weight is balanced on the top of the box, on what is known as the platform, which is only a few inches wide.

Another crucial part of the shoe is the shank. The shank of a pointe shoe is like an insole in the sense that it is positioned directly under the foot, and is typically made from leather. The leather molds to the shape of the dancer's foot to support her when en pointe. The wings of a pointe shoe extend from the box and attach to the shank to provide additional strength to the side of the shoe. The shoe is covered in satin to cover the leather, fabric, glue, and other unsightly features of the shoe.

Pointe shoes can last for varying amounts of time depending on the dancer, her foot shape, the brand of shoe, and the difficulty of the ballet she is currently dancing. On average, a pointe shoe will last a professional ballerina for about one performance, however sometimes a dancer will have to change her shoes once or twice in a show for a difficult role. Dancers also generally go through a pair of pointe shoes a day in rehearsals and ballet classes. This short life span is due to the materials used. The leather, fabric, paper, and cardboard are the current ideal materials for making a pointe shoe because they mold to the dancer's foot easily, are lightweight, and are quiet on stage. Unfortunately, all of these materials as well as the glues used breakdown easily in hot and sweaty conditions typically experienced while wearing a pointe shoe. A ballet company will generally provide shoes for their dancers but at the rate dancers go through the shoes, ballet companies like New York City Ballet find themselves spending over $500,000 on over 8,500 pairs of shoes per year.

Some advances in pointe shoes have been made. The most revolutionary change was made by a company called Gaynor Minden who switched the box and shank of their shoes to elastomeric. The elastomeric in the shoes has extended the life of the shoe compared to a traditional leather and fabric shoe, however the Gaynor Minden shoes still give out and provide an entirely different feel while dancing.

SUMMARY

An objective of the invention is to improve the usable life of a ballet pointe shoe as well as decreasing the risk of injury by using composite materials in parts of the shoe without compromising fit, performance, or comfort. By changing the antiquated materials used in a traditional pointe shoe to a composite material, dancers could see an increase in shoe life and better stability, and dance companies would spare the expense of having to buy new shoes so frequently.

Carbon fiber is made from long strands of mostly carbon atoms that are woven together. Because of this, there are many thicknesses, flexibilities, and types of carbon fiber that can be used. One of these is pre-impregnated carbon fiber, which already contains an epoxy resin. Instead of requiring additional adhesive, pre-impregnated carbon fiber already contains the required resin that is needed to mold the carbon fiber. The resin is cured with heat and is able to withstand hot and wet conditions without breaking down. Additionally, the carbon fiber can be unidirectional or bidirectional, which refers to whether the fibers are woven parallel or perpendicular, subsequently. Bidirectional carbon fiber is more flexible than unidirectional carbon fiber.

In an exemplary embodiment, an insert is provided for a ballet pointe shoe including a heel at one end of the shoe, a box at an opposite end of the shoe for encapsulating a dancer's toes, a platform on which a dancer's weight is balanced, and a cover. The insert includes an aft section positionable adjacent the heel or between the heel and the box, and a forward section positionable adjacent the platform and under the box. A distal end of the forward section is shaped in complement to the platform. The insert is formed of carbon fiber.

The thickness of the carbon fiber may be at least 0.024 inches, at least 0.036 inches, or generally between 0.024-0.072 inches. Alternatively, the thickness of the carbon fiber may be selectable by a user according to a number of layers of carbon fiber, where each layer of carbon fiber may be 0.012 inches thick. In some embodiments, the carbon fiber may be pre-impregnated with an epoxy resin. In this context, the layers may be secured together via the epoxy resin. The distal end of the forward section may be substantially straight.

In another exemplary embodiment, a ballet pointe shoe includes the carbon fiber insert of the described embodiments. The ballet pointe shoe may additionally include a shank extending from at least a middle portion of the shoe to the platform, where the insert is positioned in the shoe on top of the shank. Alternatively, the shoe may be without a shank such that the insert is the only support between the dancer and the cover.

The box may be formed of carbon fiber, and/or the cover may be formed of Kevlar.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and advantages will be described in detail with reference to the accompanying drawings, in which:

FIGS. 1 and 2 are computer simulations of a ballet pointe shoe for a finite element analysis;

FIG. 3 shows the carbon fiber insert according to the described embodiments; and

FIG. 4 shows a ballet pointe shoe with the carbon fiber insert in place.

DETAILED DESCRIPTION

Identifying an optimum carbon fiber was achieved using a finite element analysis. Details of the finite element analysis are described in the noted provisional application, which has been incorporated by reference. Generally, the finite element analysis illustrated how various materials will function in various conditions.

A pointe shoe insert was made by utilizing carbon fiber and epoxy resin. Multiple inserts of varying thicknesses were made. The inserts were able to withstand both dancing and failure tests. Comparable inserts were created that gave the same feel as a traditional pointe shoe but never broke down or loosened. The shoes held their shape and feel in both the ballet class and performance setting. By changing traditional pointe shoe shanks from cardboard and leather to carbon fiber, and/or adding a carbon fiber insert to the traditional pointe shoe, the shoes experience extended life and improved balance while maintaining an equivalent appearance.

Tests were conducted in multiple tiers. In a first tier, finite element analysis was used to design the pointe shoe, and computer aided tests were conducted to determine optimum materials as well as identify expected failure points. FIGS. 1 and 2 show the computer design of the shoe 10 for the finite element analysis. As shown, the shoe 10 for the simulation includes the shank 12 and the wings 14, which both terminate adjacent the platform. Results of the analysis demonstrated that stress will concentrate on the wing blocks and underneath the arch of the foot (mid shank).

In a second tier, a complete series of ballet exercises were performed in the pointe shoes for 15 minutes, and break in conditions of the shoes and comparisons with traditional shoes were recorded. Each carbon fiber insert was constructed with a thickness of 0.012 inches, and tests were conducted using one and up to six layers of carbon fiber inserts (each layer representing 0.012 inches thickness). The multiple layers were secured together by an adhesive, or with the pre-impregnated carbon fiber, by heating the inserts to activate the adhesive. The details and results of the second tier test are described in the provisional application.

In a third tier, increased intensity of dancing and ballet tests on the shoes were performed by wearing them for one ballet class (1 hour and 30 minutes). The details and results of the third tier test are also described in the provisional application.

It was determined that the shoes with three layers of carbon fiber in the insert was optimal. That is, a carbon fiber insert with a thickness of 0.036 inches provided the best results. The 0.036 inches insert provided an appropriate amount of stiffness while still enabling the dancer to move in and control the shoes. It was reported that the dancer's dancing was improved (stability, technique, confidence) while wearing the shoes as it was easier to maintain balance.

In a fourth tier test, a complete ballet variation was performed with the carbon fiber inserts in the shoes to simulate performance conditions. All of the insert strengths that were tested (including two, three and six layers of carbon fiber—i.e., 0.024 inches thickness, 0.036 inches thickness and 0.072 inches thickness) were able to withstand this testing. The shoes all continued to provide the same amount of support that they did from the beginning of the testing without noticeable change or “break in.” The carbon fiber inserts thus enable the shoes to exceed the life of a traditional pointe shoe and hold the same feel regardless of the amount and intensity of dancing.

In a fifth tier test, it was attempted to bend the shoes to a failure point. Inserts with 1, 2, 3, and 6 layers of carbon fiber were bent to increasing angles until they could not be bent any more. None of the carbon fiber inserts broke. It is noted that this testing was extreme and far more strenuous of an angle than a person's foot would ever be able to get to in a pointe shoe.

FIG. 3 shows the insert 110 for the ballet pointe shoe. FIG. 4 shows the insert 110 in a ballet pointe shoe 16. The ballet pointe shoe generally includes a heel 18 at one end of the shoe, and a box 20 at an opposite end of the shoe for encapsulating a dancer's toes. The shoe 16 also includes a platform 22 on which the dancer's weight is balanced. A cover 24 surrounds and defines the shoe components.

The insert includes an aft section 112 that is positionable adjacent the heel 18 of the shoe or between the heel 18 and the box 20 of the shoe. As shown in FIG. 4, the aft section 112 is positioned forward of the heel 18 between the heel 18 and the box 20. A forward section 114 is positionable adjacent the platform 22 and under the box 18. A distal end 116 of the forward section 114 is shaped in complement to the platform 22. In an exemplary construction, the distal end 116 of the forward section 114 is substantially straight (or flat).

With reference to the discussion above, the insert 110 is formed of carbon fiber. As a result of the various tests and analyses, it was discovered that the thickness of the carbon fiber should be at least 0.024 inches and is preferably at least 0.036 inches. Overall a thickness of the carbon fiber should be between 0.024-0.072 inches. At thicknesses below 0.024 inches, the insert provided little or no support in use. The dancer was rolling over the box of the shoe, and the shank bent into the arch of her foot. The carbon fiber insert did not allow the dancer to control her weight when transferring from flat to pointe. Overall, there was not enough support to provide safe dancing conditions. The dancer reported that this was comparable to a shoe without a shank at all. For thicknesses greater than 0.072 inches, the carbon fiber insert made the shoe almost immobile. It took significant effort to get from the floor to pointe. The shoe was too stiff to move and control. The dancer could not use the strength in her feet to get the insert to move or bend. It was difficult for her to get her weight all the way over the box of the shoe, and she reported that it felt as if the shoe was trying to pull her back down off pointe.

The thickness of the carbon fiber may be selectable via a user according to a number of layers of carbon fiber, where each layer of carbon fiber is 0.012 inches thick. In this context, the carbon fiber may be pre-impregnated with an epoxy resin. With multiple layers of carbon fiber selected by the user, the layers can be secured together via the epoxy resin. A curing process using heat or the like may be used, or the resin may be activated in a different way.

In some embodiments, the shoe 16 may additionally include a shank 26 (under the insert 110 in FIG. 4) that extends from at least a middle portion of the shoe to the platform 22, where the insert 110 is positioned in the shoe on top of the shank 26. Alternatively, the shoe 16 may be without a conventional shank such that the insert 110 is the only support between the dancer and the cover 24.

The invention contemplates manufacturing the box 20 of the shoe out of carbon fiber as well, and there may be no need to ever replace the shoe. With a carbon fiber box 20 and the insert of the described embodiments, as well as stronger fabric instead of satin for the cover 24 (e.g., Kevlar), the shoe would never break down or be subject to fraying in the fabric.

The inserts of the described embodiments can be used in addition to a traditional ballet pointe shoe shank or instead of a traditional shank. The inserts can be inserted on top of a traditional shank to increase the life of the traditional shoe and then once the traditional shank has broken down, the inserts can be used on their own. Since the carbon fiber inserts exceed the life of a traditional shank, dancers using the carbon fiber inserts will no longer have to replace their shoes as frequently, if ever, which will greatly reduce the economic burden of ballet for both families and professional companies. In addition to the financial benefits, dancers will not have to spend the time constantly breaking in and sewing new shoes.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 

1. An insert for a ballet pointe shoe including a heel at one end of the shoe, a box at an opposite end of the shoe for encapsulating a dancer's toes, a platform on which a dancer's weight is balanced, and a cover, the insert comprising: an aft section positionable adjacent the heel or between the heel and the box; and a forward section positionable adjacent the platform and under the box, a distal end of the forward section being shaped in complement to the platform, wherein the insert is formed of carbon fiber.
 2. An insert according to claim 1, wherein a thickness of the carbon fiber is at least 0.024 inches.
 3. An insert according to claim 1, wherein a thickness of the carbon fiber is at least 0.036 inches.
 4. An insert according to claim 1, wherein a thickness of the carbon fiber is between 0.024-0.072 inches.
 5. An insert according to claim 1, wherein a thickness of the carbon fiber is selectable by a user according to a number of layers of carbon fiber, and wherein each layer of carbon fiber is 0.012 inches thick.
 6. An insert according to claim 5, wherein the carbon fiber is pre-impregnated with an epoxy resin.
 7. An insert according to claim 6, wherein the layers are secured together via the epoxy resin.
 8. An insert according to claim 1, wherein the carbon fiber is pre-impregnated with an epoxy resin
 9. An insert according to claim 1, wherein the distal end of the forward section is substantially straight.
 10. A ballet pointe shoe comprising: a heel at one end; a box at an opposite end for encapsulating a dancer's toes; a platform on which a dancer's weight is balanced; a cover; and an insert, the insert including: an aft section positionable adjacent the heel or between the heel and the box, and a forward section positionable adjacent the platform and under the box, a distal end of the forward section being shaped in complement to the platform, wherein the insert is formed of carbon fiber.
 11. A ballet pointe shoe according to claim 10, further comprising a shank extending from at least a middle portion of the shoe to the platform, wherein the insert is positioned in the shoe on top of the shank.
 12. A ballet pointe shoe according to claim 10, wherein the shoe is without a shank such that the insert is the only support between the dancer and the cover.
 13. A ballet pointe shoe according to claim 10, wherein the box is formed of carbon fiber.
 14. A ballet pointe shoe according to claim 10, wherein the cover is formed of Kevlar.
 15. A ballet pointe shoe according to claim 10, wherein a thickness of the carbon fiber is at least 0.024 inches.
 16. A ballet pointe shoe according to claim 10, wherein a thickness of the carbon fiber is at least 0.036 inches.
 17. A ballet pointe shoe according to claim 10, wherein a thickness of the carbon fiber is between 0.024-0.072 inches.
 18. A ballet pointe shoe according to claim 10, wherein a thickness of the carbon fiber is selectable by a user according to a number of layers of carbon fiber, and wherein each layer of carbon fiber is 0.012 inches thick. 